Other
Shrews, birds or unknown bat species.
Date of recording: 2024-06-12 Recorded by: Kim Kuijlen, Sarah Mahie Audio file:
These two calls are a nice example of shrew calls. In this case, most likely a common shrew (Sorex araneus). Unlike bat sounds, shrew sounds are low-amplitude, multi-harmonic, broadband and often modulated. Nevertheless, they can look a lot like type A bat social calls as seen on the Type A social call page. Shrews are very vocal animals and studies suggests that shrews may use the echoes and reverberations of their calls for identifying routes through their habitat or for probing habitat type - making shrew echo orientation not that far off from bat echolocation (Siemers et al., 2009).
The following recording contains a series of calls produced by a greater white-toothed shrew (Crocidura russula). Around 1,000 s and 3,120 s in the recording, the shrew also produced a fast trill. Something that might be confused with a type D social call of a bat.
Date of recording: 2024-06-20 Recorded by: Roald Dorrestein Audio file:
The calls in the next two recordings do show a little similarity to common shrew calls, but the trills appear to be too slow in comparison to reference material of Stuart Newson, et al. (2020) and Neil Middleton (2020). After personal contact with Stuart Newton, his thoughts about these calls were as follows:
"The most likely possibility is that these calls were produced by a Crocidura species. In the Netherlands, I have done a lot of work on the sound identification Crocidura russula, but it very rarely produces pronounced trills in its calls – I don’t think that I can completely exclude this possibility, but I would be surprised if they were produced by this species. This leaves me with Crocidura leucodon. This is the only shrew species in the Netherlands I think, where I have only seen a small number of recordings and I don’t understand its vocalisations." "I discussed and showed these recordings with a colleague of mine, Simon Gillings, today, which further confirmed my thinking that the calls here couldn't have been produced by a bird species."
The map shows the distribution of C. leucadon in the Netherlands and the location of the recording is indicated as a red X. The recording was made 40 kilometers away from the species' expected range.
Other animals, like birds, have calls that may resemble type A or type D social calls of bats aswell. For example the calls of the common blackbird (Turdus merula), a species that is regularly encountered during bat surveys. Note that all these call are on a very low frequency: almost all is below 20 kHz.
Date of recording: 2024-06-19 Recorded by: Douwe van der Wijk Audio file: 914901
In this recording, a bat, shrew and bird are present at the same time below 30 kHz. The calls around 20 kHz are from a common noctule (Nyctalus noctula), the calls around 15 kHz are from a greater white-toothes shrew (Crocidura russula) and the song around 5 kHz is from a common chiffchaff (Phylloscopus collybita).
Date of recording: 2024-07-08 Recorded by: Zsuzsanna Szabo Audio file: 919471
These bat calls were not recorded in the Netherlands, but in Minas Gerais, Brazil.
It amazes me how bats all over the world, still have recognizable social calls and feeding buzzes. The bat species in this recording are assumed to be the Western bonneted bat (Eumops perotis), with it's social calls in the snippit on the right, and the Brazilian free-tailed bat (Tadarida brasiliensis), with it's social calls and feeding buzz in the snippits below. Less than 10% of Brazil is minimally surveyed and for nearly 60% of Brazil there is not a single record of bat species (Bernard, 2010).
Date of recording: 2022-09-19 Recorded by: Sarah Mahie, Boaz van Die Audio file: 909905
And last but not least, insect sounds are also regular by-catch during bat surveys. It is possible to identify te species of crickets based on their sound, just like bats. Hence why some cricket-specialists use bat detectors to survey them (EIS, no date). Besides crickets, around 20% of moths all over the world have evolved the ability to emit ultrasonic acoustic emissions as a defence tactic agains predating bats (Barber et al., 2022). The high frequency clicking of the moths interfere with the echolocation of bats (Corcoran et al., 2009).
I, Sarah, have been a fond breeder of multiple species of dermestid beetles for multiple years. I have found only one article from 1968 and one YouTube video about the chirping sound that larder beetles (Dermestes lardarius) can produce. However, I might be the first to document the sound of black larder beetles (Dermestes ater) and African larder beetles (Dermestes haemorrhoidalis). Even though I identify bats based on their acoustic specifications on a daily basis some months, somehow I was still surprised to see such a clear difference in the sound of the different dermestid beetle species.
All recordings are licensed under the following Creative Commons Attribution-NonCommercial-NoDerivs 4.0 license and in courtesy of Sarah Mahie.
All sonograms are screenshots of the recordings imported in the ultrasound analysis software BatExplorer 2.2 (Elekon, Switzerland).
Literature list:
- Aaron J. Corcoran, Jesse R. Barber & William E. Conner (2009). Tiger Moth Jams Bat Sonar. Science. 325(5938). DOI: 10.1126/science.1174096
- EIS (no date). Batdetector. Retrieved from: https://www.eis-nederland.nl/batdetector
- Enrico Bernard, Ludmilla Aguiar and Ricardo Machado (2010). Discovering the Brazilian bat fauna: A task for two centuries? Mammal Review. 41: 23 - 39. 10.1111/j.1365-2907.2010.00164.x.
- Björn M. Siemers, Grit Schauermann, Hendrik Turni and Sophie von Merten (2019). Why do shrews twitter? Communication or simple echo-based orientation. Biology Letters. 5(5): 593–596. doi: 10.1098/rsbl.2009.0378
- Jesse R. Barber, David Plotkin, Juliette J. Rubin & Akito Y. Kawahara (2022). Anti-bat ultrasound production in moths is globally and phylogenetically widespread. Proceedings of the National Academy of Sciences of the United States of America. 119(25). https://doi.org/10.1073/pnas.2117485119
- Jon Russ (2021). Bat Calls of Britain and Europe: a Guide to Species Identification. Pelagic Publishing.
- Niel Middleton (2020). Is That a Bat? A guide to non-bat sounds encountered during bat surveys. Pelagic Publishing.
- S.W. Bailey, R.W. Lemon (1968) Sound production by the larder beetle, Dermestes lardarius Linnaeus (Coleoptera Dermestidae). Journal of Stored Products Research. 4 (3): 271-273.
- Stuart Newson, Neil Middleton and Huma Pearce (2020). The acoustic identification of small terrestrial mammals in Britain. British Wildlife. 32(3).
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